Process for treating oils



9, 1941. w. A. scHuLzE 2,255,394 PROCESS FOR 'mm'rme oILs Filed Nov. 9,193a CRUDE PETROLEUM I OH.

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. I I E RESIDUUM GAS TOVAPOR 9 GASOLINE RECOVERY PLANT '5 I I C4- IHYDROCARBONS SUBSTANTIALLY c VAPOR RECOVERY AND LIGHTER CRACKED GASOLINEGASOLINE SODIUM SULFIDE STABILIZATION souo- COPPER 47 TREATING PLANT I6)5 FINISHEb GASOLINE STORAGE INVENTOR. w.A.scI-|uI zE \QUQ W ATTORN S.

Patented Sept. 9, 1941 UNITED STATES PATENT OFFICE PROCESS FOR TREATINGOILS Walter A. Schulze, Bartlesville, Okla., assignor o PhillipsPetroleum Company, a corporation of Delaware Application November 9,1938, Serial No. 239,730

Claims. (Cl. 196-30) This invention relates to the refining treatment ofmercaptan-containing light hydrocarbon 'form without production andconsequent introduction into the oil of various undesirable compoundsformed as by-products in nearly all of I the sweetening methods usedheretofore.

A further object is to avoid instability of the product by selectivetreatment, under carefully controlled conditions, of stocks susceptibleto gum and color formation, and to simplify treatment for stocks whichare' inherently stable, thus contributing to ease and economy ofoperation.

Unrefined petroleum products contain mercaptans, commonly called sourelements, which give the oil undesirable odor, and render it corrosiveand unstable. Until recently these compounds have been customarilyremoved or altered, by the so-called doctor process, a laborious,cumbersome and very uneconomical chemical treatment with alkalineplumbite and sulfur. In some instances, e. g., natural gasoline, thesweetening action has been accomplished through the use of alkalinehypochlorite solutions, but this method, too, has not provedsatisfactory in most cases due to the introduction into the oil ofundesirable constituents as bad as those originally present.

Recently, however, sweetening of petroleum products has beenaccomplished with much improved results through the use of the so-calledCopper sweetening methods. These methods have been referred to in theliterature as the "Solution process and the Solid process respectively.The Solution process employs the copper solutions described in U. S.Patent- 1,964,219 issued to Schulze and Frey, June 26, 1934. The coppersolutions are maintained active and the oxidation potential controlledas shown in U. S. Patent 2,058,720 to Reid and Schulze, dated October27, 1936. Following treatment with the copper solutions the petroleumoils are treated with alkaline sulfide solutions as shown in U. S.Patent 1,980,555 to Schulze and Frey,

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dated-November 13, 1934. This latter treatment is commonly referred toas the stabilizing step. Oils which are treated with copper solutionscontain traces of organic copper compounds which cause instability ofthe treated gasoline with respect to color and gum formation; hence thetraces of copper compounds must be removed by the stabilizing solution.

The so-called Solid copper sweetening process. as described in a patentby Buell, Patent No. 2,094,485, dated September 28, .1937, employs moistsolid copper reagents for sweetening. These reagents are prepared byimpregnating adsorbent carriers such as fullers earth with aqueoussolutions containing cupric and chloride ions. The petroleum productsare sweetened by filtration through these reagents. With proper control,the treated product does not contain even traces of copper compounds andhence no stabilizing treatment is necessary. The processis limited,however, to those fractions of petroleum products which are relativelystable and do not readily form gum and colored compounds.

I have found that all of the light products from crude petroleum fluidmay be copper sweetened in a highly satisfactory and economical mannerby selective treatment, under carefully controlled conditions, of stockssusceptible to gum and color formation, and to simplify treatment forstocks which are inherently stable.

I have discovered that petroleum fractions which are substantially freeof unsaturated hydrocarbons may be treated under controlled conditionsby means of the Solid copper reagent without depreciation in color orgum stability of these products or of blends of these products withother less stable fractions. These sweetened fractions which arecomposed predominantly of parafiin and naphthenic hydrocarbons are freeof copper compounds and do not require a stabilizing treatment.

I have discovered furthermore that those petroleum fractions whichcontain substantial quantitles of unsaturated hydrocarbons containingseven or less carbon atoms may likewise be treated satisfactorily withthe solid reagent with results similar to those obtained on fractionscomposed of saturated hydrocarbons. However, those fractions containingappreciable quantities of unsaturated hydrocarbons with eight or morecarbon atoms must be treated by the solution method since such fractionsare relatively unstable and tend to become discolored and to formLikewise, these fractions containing the higher unsaturated hydrocarbonscontain traces of copper which accelerate color and gum formation. Thus,the solution method must be used to sweeten these fractions since thereis no deterioration in the product during the "Solution treatment andthe final stabilizing step insures the removal of traces of copper sothat no deterioration occurs during stora e.

My invention may be best understood by referring to the drawing, whereinthere is shown diagrammatically one embodiment of my inven-.

tion. Crude petroleum oil I is separated in a flashing or stabilizationunit 2 into light hydrocarbons 4 and stabilized crude oil 3. The lighthydrocarbons 4 after removal of hydrogen sulfide,

if present, may be sent directly to the Solid than that of gasoline maybe taken off the bubble tower, e. g., kerosene or light naphthafractions may be obtained simultaneous with the gasoline fraction 1. Insuch event these fractions may be treated in a manner similar to thegasoline fraction.

The topped crude i is then subjected to cracking in a cracking unit 8 inthe usual manner and separated into residuum 9, cracked gasoline H andlight hydrocarbon gases Ill. The gas I is sent to the vapor recoveryplant where the fraction termed vapor recovery gasoline II is obtained.This vapor recovery gasoline, free of hydrogen sulfide, is sweetened inthe Solid copper reagen treating plant IS. The non-condensible andnormally gaseous hydrocarbons from the flashing and cracking operationsmay be brought together and segregated l as an adjunct of the vaporrecovery operation.

The cracked gasoline H is separated into a fraction comprising thehigher boiling hydrocarbons termed herein Heavy cracked gasoline I2 andthe lower boiling hydrocarbons comprising substantially thosehydrocarbons containing seven and less carbon atoms l3. This separationof the cracked gasoline into the light and heavy fractions may be made,if desired, at the same time that the gasoline is separated from theresiduum and light gases.

The cracked gasoline fraction 13 comprising substantially thosehydrocarbons containing seven and less carbon atoms may be sent to theSolid copper reagent" treating plant i6 after removal of any hydrogensulfide which may be present. The Heavy cracked gasoline fraction,however, must be sent to the Copper solution treating plant I! where itis contacted with copper solution and stabilized with alkaline sulfidesolution.

The various gasoline fractions, after sweetening in either the Solidcopper reagent treating plant l6 or the Copper solution treating plantI1, are sent to finished gasoline storage It where they may be blendedinto motor fuels of the proper specifications.

By operating in the manner indicated above, it

has been possible to obtain extremely satisfactory finished gasolinescomprising both saturated and unsaturated hydrocarbons of both lowboiling and high boiling range. The gasoline is completely sweet, goodcolor, free of traces of copper compounds, and exceptionally stable withrespect to color and gum formation during storage. 0n theother hand whenan attempt was made to sweeten all of the fractions either as a blend,or as individual streams blended after sweetening, for example by theSolid reagent method the gasoline became colored during treatment andwas extremely unstable in storage, forming large quantities of gum andcolored compounds within a short storage interval. Likewise, when all ofthe fractions were treated by the Solution method itwas found that theplant required for treatment and for stabilization was necessarily largeand expensive. Also, the stabilization step had to be performed on allthe fractions or the finished blends deteriorated rapidly. Thus, inorder to employ the Solution method satisfactorily to all the gasolinefractions it would have been necessary to have ample stabilizingequipment for all the gasoline and also it would have meant increasedexpenditure for the treating chemicals. Therefore, when operating in themanner describedin this invention greatly improved results are obtained.

There are many modifications of this invention which will be apparent tothose skilled in the art and the limitations are defined solely by thescope of the appended claims.

I claim:

1. In a process for producing a sweet motor fuel from crude petroleumoil by steps which comprise subjecting said crude petroleum oil to amediumtemperature flashing operation to produce stabilized crude oil anda low-boiling straight run gasoline, subjecting said stabilized crudeoil to a distillation operation to produce straight run gasoline andtopped crude, subjecting said topped crude to a cracking operation toproduce a gaseous fraction containing some gasoline hydrocarbons and afraction comprising cracked gasoline, processing said gaseous fractionto recover the gasoline content, and separating said cracked gasolineinto a low-boiling fraction containing substantially seven and lesscarbon atoms per molecule and a higher-boiling fraction containing morethan seven carbon atoms per molecule, the improvement comprisingsweetening the cracked gasoline fraction containing more than sevencarbon atoms per molecule by treatment with a cupric chloride solutionof controlled chloride ion content followed by sodium sulfidestabilization, and sweetening the remaining said gasoline fractions bypassage along with dissolved air over a solid adsorbent reagentimpregnated with a solution of cupric chloride prior to blending atleast a portion of the gasoline fractions to provide a sweet motor fuel.

2. In a process for producing a sweet motor fuel from crude petroleumoil by steps comprismg subjecting said oil to a medium-temperatureflashing operation to produce stabilized crude oil and a low-boilingstraight run gasoline, subjectmg said stabilized crude oil to adistillation operation to produce straight run gasoline and toppedcrude, subjecting said topped crude to a crackmg operation to producestraight run gasoline and topped crude, subjecting said topped crude toa cracking operation to produce a gaseous fraction containing somecracked gasoline hydrocarbons which are recovered by. suitable means anda fraction comprising cracked, gasoline, the

improvement comprising fractionating said total the gasoline fractionsto produce a sweet motor fuel.

carbons boiling within the gasoline range are separated from thepetroleum oil and at least a portion of the remaining petroleum oil iscracked to produce hydrocarbons boiling within the gasoline range andcontaining quantities of unsaturated hydrocarbons, the method ofsweetening said hydrocarbons boiling in the gasoline range whichcomprises separating the cracked hydrocarbons boiling in the gasolinerange into a fraction containing seven and less carbon atoms permolecule and a fraction containing seven and more carbon atoms permolecule, sweetening said saturated hydrocarbons boiling in the gasolinerange and said unsaturated hydrocarbon fraction containing seven andless carbon atoms per molecule by treatment with a solid adsorbentreagent impregnated with a solution of cupric chloride and sweeteningsaid unsaturated hydrocarbon fraction containing seven and more carbonatoms per molecule by treatment with a solution of cupric chloridefollowed by stabilization of the sweetened fraction with respect tominute amounts of copper remaining in the sweetened oil, and blendingthe sweetened fractions into motor fuel.

4- In the process oi producing motor fuel from crude petroleum oil, inwhich low boiling saturated hydrocarbons are separated from thepetroleum oil and at least a portion of the remain- 3. In the process ofproducing motor fuel from crude petroleum oil, in which saturatedhydroing petroleum oil is cracked to produce low boiling hydrocarbonscontaining quantities of unsaturated hydrocarbons, the method'ofsweetening said low boiling hydrocarbons which. comprises separating thecracked hydrocarbons into a fraction containing seven and less carbonatoms per molecule and a fraction containing seven and more carbon atomsper molecule, sweetening said low boiling saturated hydrocarbons andsaid unsaturated hydrocarbon fraction containing'seven and less carbonatoms per molecule by treatment with a solid adsorbent reagentimpregnated with a solution of cupric chloride and sweetening saidunsaturated hydrocarbon fraction containing seven and more carbon atomsper molecule by treatment with a solution of cupric chloride followed bystabilization of the sweetened fraction with respect to minute amountsof copper remaining in the sweetened oil, and'blending the sweetenedfractions into motor fuel.

5. In the process of producing gasoline, kerosene and naphtha from crudepetroleum oil in which a saturated hydrocarbon fraction boiling in thegasoline range, kerosene and naphtha are separated from petroleum oiland at least a portion of the'remaining petroleum oil is cracked toproduce hydrocarbons boiling within the gasoline range and containingquantities of unsaturated hydrocarbons, the method of sweetening i saidfractions which comprises separating the cracked hydrocarbon fractionboiling within the gasoline range into a fraction containing seven andless carbon atoms per molecule and a fraction containing seven and morecarbon atoms per molecule, sweetening said saturated hydrocarbonsboiling in the gasoline range, kerosene and naphtha and said unsaturatedfraction containing seven and less carbon atoms per molecule bytreatment with a solid adsorbent reagent impregnated with a solution ofcupric chloride and sweetening said unsaturated hydrocarbon fractioncontaining seven and more carbonatoms per molecule by treatment with asolution of cupric chloride followed by stabilization of the sweetfraction with respect to minute amounts of copper remaining in thesweetened oil.

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